1. Field of the Invention
The present invention relates to a penetration reinforcing agent for preventing aging of concrete, a process for preparing the penetration reinforcing agent, and a method of applying the penetration reinforcing agent onto concrete. More specifically, the present invention relates to a penetration reinforcing agent for preventing aging of concrete which is prepared by using an inorganic silicate compound having an ethoxy or methoxy group and a monomer having a hydroxyl (OH) group, a process for preparing the penetration reinforcing agent, and a method of applying the penetration reinforcing agent onto concrete. When the penetration reinforcing agent of the present invention is applied onto the surface of a concrete structure by using a spray gun or a brush, it penetrates the concrete structure where it is hydrolyzed by water existing within the concrete to form silica (SiO2) having a particle size of several nanometers, gelled by a sol-gel process and reacts with concrete hydrates, so that internal pores of the concrete structure are compactly filled with the reaction products. Therefore, the penetration reinforcing agent of the present invention is effective in enhancing the strength of the concrete structure, inhibiting penetration of aging materials into the concrete structure, improving waterproofness of the concrete structure and preventing neutralization of the concrete structure.
2. Description of the Related Art
In general, steel-reinforced concrete structures have been surface-coated with organic or inorganic materials in order to inhibit aging and improve the waterproof performance of the structures. Organic polymeric materials, such as silicone, epoxy and urethane resins, have been used as conventional penetration reinforcing agents. In the case where an organic polymeric material is used as a penetration reinforcing agent, vibration, water vapor pressure and difference in the elastic modulus between the penetration reinforcing agent and concrete cause various problems, such as destruction or peeling of coating layers. Further, organic polymeric materials possess fundamental limitations in their use because they are not integrated with concrete, which is an inorganic material.
Korean Patent Laid-open No. 1998-076357 discloses a method of preventing dewing in concrete buildings, the method comprising the steps of applying a silicone emulsion onto the surface of concrete to form a waterproof sealing layer inside the concrete surface, applying a cement-based compound onto the concrete surface, within which the waterproof sealing layer is formed, to form a waterproof coating layer, and plastering a mortar, which is prepared by replacing a portion of water with a silicone emulsion, on the said waterproof coating layer to form a mortar layer. According to this method, however, since the formation of the final waterproof layer involves three steps, considerable construction costs are incurred and construction period is extended. In addition, since there are large differences in the mechanical properties, such as strength, elastic modulus and stress-strain between the waterproof layer and the concrete, peeling and delamination of the waterproof layer from the concrete inevitably occur after the passage of a predetermined period of time.
Further, Korean Patent Laid-open No. 2001-0064300 discloses a penetrative waterproofing agent in which an aqueous alkali metal silicate solution is applied onto the surface of concrete to penetrate the concrete surface and the penetrated alkali metal silicate reacts with calcium hydroxide present in the concrete to form an insoluble gel, thus achieving waterproof effects. Especially, a silicate compound containing calcium as a divalent alkali metal, potassium and lithium, which is represented by a metal alkoxide, penetrates concrete to enhance the watertightness of the concrete, thus attaining waterproof effects. However, since water as a solvent is used in a large amount of 65 to 85% by weight in the above invention, the amounts of materials substantially reacting with the concrete are relatively small, causing deterioration in the performance of the waterproofing agent Further, since the alkali metal silicate, such as sodium silicate, potassium silicate or lithium silicate, rapidly reacts with the concrete, gelling occurs on the concrete surface before the waterproofing agent penetrates the concrete, and as a result, the waterproofing agent cannot be penetrated to an optimum depth as needed. Moreover, the above waterproofing agent cannot prevent decomposition of the concrete arising from seasonal variations due to its hydrophilicity.